This invention relates to a household electric toaster but aspects of this invention can be used in other heating appliances, particularly toasters for commercial use.
Household toasters commonly have a control chamber separated by a vertical front frame plate from a toasting chamber. A bread carriage plate, termed a xe2x80x9cbread lifter platexe2x80x9d herein, is slidably received on a support post in the control chamber and carries a pair of bread supports, termed xe2x80x9cbread liftersxe2x80x9d herein, that extend into and at least partially through the toasting chamber between heating elements therein. The lifter plate and accordingly the bread lifters are vertically-movable between a lowered position for holding bread or other food items in position to be toasted and a raised position for permitting the bread or other food items to be placed on or removed from the bread lifters.
Some toasters have only one bread lifter and some have more than two bread lifters. For ease of discussion, this invention is disclosed for use in a toaster configuration which has two bread lifters, such presently being the most common configuration. However, as will become apparent, aspects of this invention described below can be used in other toaster configurations.
In many toasters, the bread supports are part of a vertically movable support carriage to which the bread supports are connected. Spring means biases the support carriage upwardly so that the bread supports are normally in their upper, non-toasting position. The support carriage can be lowered to the toasting position by manipulation of a control lever, termed a xe2x80x9clifter extensionxe2x80x9d herein, accessible from outside the housing. During a toasting cycle, a latch mechanism holds the support carriage with its bread supports in their lowered, toasting position. User-adjustable electric means controls the toasting cycle times during which the bread supports are latched in their lowered position in order to toast the food items to the desired toast color.
A latch comprising a pivotally mounted armature or latch plate biased away from the face of the solenoid coil hooks over an upwardly-facing surface on the bread carriage plate when the carriage plate is lowered to its toasting position. To terminate a toasting cycle, a solenoid switch is closed, causing the solenoid to be energized, whereupon the latch plate is pulled toward the solenoid coil and unhooked from the carriage plate. The bread lifter spring returns the bread lifter assembly to its raised position during which time the bread lifter that was holding the power switch closed moves upwardly away from the power switch and the power switch opens.
In order to energize the solenoid coil at the end of the toasting cycle, a bimetal heat sensing assembly in the toasting chamber drives a horizontally-movable switch operating shaft outwardly toward a movable switch contact located in the control chamber. The duration of the toasting cycle and, therefore, the resultant degree or xe2x80x9ccolorxe2x80x9d to which the toast is toasted, is adjusted by a toast color control cam that moves the switch contacts nearer to or farther from the end of the bimetal-driven switch operating shaft, so that the excursion of the shaft from the beginning of a toasting cycle to the end of a toasting cycle required to close the solenoid switch can be changed to obtain different toast colors.
Notwithstanding the several elements that comprise a household toaster, household toasters are usually remarkably inexpensive. The low cost partly results from the use of sophisticated manufacturing and assembling techniques. There is however, an ever-present need to reduce the costs of toasters in order to provide toasters to the public at low costs and meet the demands of a competitive industry.
An object of this invention is to provide an improved household electric toaster. More particularly, an object of this invention is to provide a rugged, high quality household toaster which can be manufactured at relatively low cost. To accomplish these objects, this invention utilizes improvements in the following areas of toaster construction and operation:
1. The toaster has a metal body and plastic end panels. The end panels have cooling inlet vents near their lower ends that admit ambient air into the ends of the toaster. The flowing air flows outwardly through air outlet vents in the top wall of the metal body. The cooling is sufficient to enable the use of an inexpensive plastic material, preferably polypropylene, for molding the end panels. In contrast, plastic end panels are normally made from plastic materials that have a greater heat rating.
2. Each bread lifter is made entirely from a wire rod and is connected to the lifter plate without the use of fasteners, welding or soldering and, for ease of assembly, in a manner that prevents rotation of the lifter about a vertical axis.
3. The bread lifter extension is made entirely from a wire rod.
4. A toast color cam is made entirely from a single piece of sheet metal and is supported by the front frame plate of the toaster.
Other objects and advantages of this invention will become apparent in view of the following description taken in conjunction with the accompanying drawings.